In order to form color images, a silver halide color printing material is usually subjected to a series of processing steps after light exposure. In more detail, a light-exposed silver halide color photographic printing material is subjected to a color development step, thereby a color developing agent reduces light-exposed silver halide to form developed silver. At the same time the color developing agent itself is oxidized to form an oxidation product of the color developing agent, which reacts with couplers to form colored dyes. Then, in the subsequent silver removing step, the developed silver is oxidized by an oxidizing agent (ordinarily, called a bleaching agent) and further removed by fixing together the silver halide remaining without effecting the color developing reaction. Accordingly, dye images corresponding to the light exposure are formed. Furthermore, if desired, a stabilization bath for stabilizing dye images is employed.
Within the silver removing step, it is possible to utilize two separate baths. One bath is a bleach bath containing an inorganic oxidizing agent such as a potassium ferricyanide, a dichromate, etc., or an organic chelating compound such as an aminopolycarboxylic acid metal complex salt, etc. Another bath is a fix bath containing a silver halide solubilizing agent such as a thiosulfate, etc. Furthermore, it is possible to utilize both of these baths in one bath as a blix bath. If an inorganic bleaching agent is used in the blix solution, it is difficult to use a silver halide solubilizing agent in the same processing solution due to the very strong oxidizing power of the inorganic bleaching agent. Accordingly, an organic chelating compound such as an aminopolycarboxylic acid metal complex salt, etc., is generally used as the bleaching agent.
Formation of colored dyes is composed of two steps. That is, the oxidation product of a developing agent formed in a color development step reacts with a coupler to form a colorless leuco compound which is an intermediate of the coupler. The leuco compound is further oxidized with the oxidation product to form a colored dye. The formation of the colored dye from the leuco compound by only a color development step is generally insufficient. The leuco compound is further oxidized with a bleaching agent in a bleach bath or a blix bath to form a complete colored dye. Therefore, when the bleaching agent in a bleach bath or a blix bath does not exhibit a sufficient oxidizing power due to factors such as the fatigue of the bath, etc., the leuco compound remains partially unreacted and does not form a colored dye. This causes insufficient color reproduction even when using an inorganic bleaching agent such as a potassium ferricyanide, a dichromate, etc., for the bleach bath. In particular, the oxidizing power of a bleaching agent in a blix bath is known to be relatively weak. Accordingly, when the blix processing is performed directly after the step using a processing solution containing a reducing agent (e.g., the step using a color developer), the leuco compound does not form a colored dye by the action of the reducing agent carried in the blix solution by photographic materials. Furthermore, the colored dye once formed is reduced and converted into the leuco compound by the action of the reducing agent carried in the blix solution by photographic materials. Accordingly, the coloring density is decreased and sufficient color reproduction is not obtained. A cyan dye is particularly likely to be converted into the leuco compound and thus the coloring density thereof is greatly decreased. Therefore, when utilizing a blix solution in which a strong bleaching agent cannot be used, the conversion of the cyan dye into the leuco compound is a big trouble.
The above-described trouble can be overcome if one of the following three methods can be carried out. The first method is the most direct one, and involves using an oxidizing bath containing a potassium ferricyanide, dichromate, etc., having sufficient oxidizing power. This bath is used separately from the blix bath. However, due to the pollution problem created by he waste solution and the demand for faster processing steps, this method is not practical. The second method involves using a cyan coupler capable of forming a dye which is reluctant to convert into the leuco compound by reduction during blix processing. However, in spite of various investigations over a long period of time, cyan couplers having sufficiently desirable properties have not been discovered. The third method involves reducing the load on the bleaching agent in a blix bath. The bleaching agent in a blix bath is involved in oxidizing leuco compounds into colored dyes as well as in dissolving off silver in photographic materials from the system with a silver halide solubilizing agent. Accordingly, if too much of the bleaching agent strength is applied to the silver removing reaction, the oxidizing power of the bleaching agent for oxidizing the leuco compounds will be lost. This results in decreasing the coloring density of cyan dyes. With this problem in mind, there has been proposed a method wherein a compound such as a halogen ion, ethylene oxide, or a mercapto compound, is added to the blix bath to promote the silver removing reaction. This prevents the conversion of the cyan dyes into the leuco compounds. However, even by using this method, insufficient results are attained.